My main box has three hard drives, two PATA in a master/slave configuration, and one SATA. I use the SATA exclusively for media storage, but it seems that the BIOS is now only detecting the SATA. This means I get error 21 from GRUB and cannot get into any of my OSes.

I replaced the IDE cable, and have checked that the controllers are active in the BIOS but there is still no luck and the sockets are displayed as [Not Detected] in my BIOS.

Scratch that, just tried to boot into mint 11 (installed from the cover disc of LXF), gdm login screen froze so I forced a reboot, and again the PATA drives are not detected. What I didn't mention at first (I didn't think it would be relevant) is that the first time I booted into mint, it froze up and it was after forcing a reboot on this that the problem first occurred.